冻胀力属于（）
A、永久荷载
B、可变荷载
C、偶然荷载
D、被动荷载
参考答案：B
看图并完成下列句子。
This is a picture. We can see it's ___________ ___________. His father
is ___________ ___________ ___________. His mother is ___________
___________ ___________. He and his sister are ___________ ___________
___________. They are playing a game.
